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3 years ago

An atom of gold has a mass of 3.271 x 10-22g. How many atoms of gold are in 5.00g of gold?

1 answer:

3 0

To get the number of gold atoms, you have to divide the mass of the gold by the mass of the gold atom. It follows this simple equation $\frac{mass of gold}{mass of gold atom}$ .

Let x be the number of gold atoms. Plug in the values to a calculator.

x = $\frac{5.00g}{3.271 x 10-22g}$
Both have the same units so the unit gram(g) can be cancelled.
x then would be equal to 1.53x10^22. So there are 1.53x10^22 atoms of gold in 5 g of gold

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Complete and balance each of the following equations for gas evolution reactions HCl(aq)+ZnS(s)>

DENIUS [597]

2HCl(aq) + ZnS(s) ⇒ ZnCl₂(aq) + H₂S(g)

<h3>Further explanation </h3>

Equalization of chemical reactions can be done using variables. Steps in equalizing the reaction equation:

1. gives a coefficient on substances involved in the equation of reaction such as a, b, or c, etc.
2. make an equation based on the similarity of the number of atoms where the number of atoms = coefficient × index (subscript) between reactant and product
3. Select the coefficient of the substance with the most complex chemical formula equal to 1

Reaction

HCl(aq) + ZnS(s) ⇒ ZnCl₂(aq) + H₂S(g)

1. give equation

aHCl(aq) + bZnS(s) ⇒ ZnCl₂(aq) + cH₂S(g)

2. make an equation

H, left=a, right=2c⇒a=2c(eq 1)

Cl, left=a, right=2⇒a=2⇒c=1(from eq 1)

Zn, left=b, right=1⇒b=1

So the equation :

2HCl(aq) + ZnS(s) ⇒ ZnCl₂(aq) + H₂S(g)

4 0

3 years ago

Calcium carbonate is often used as an antacid. Your stomach acid is composed of HCl at a pH of 1.5. If you ate toooo much Turkey

stiks02 [169]

<u>Answer:</u> 0.0237 g of calcium carbonate would be required to neutralize the given amount of HCl

<u>Explanation:</u>

pH is defined as the negative logarithm of hydrogen ion concentration present in the solution

$pH=-\log [H^+]$ .....(1)

Given value of pH = 1.5

Putting values in equation 1:

$1.5=-\log[H^+]$

$[H^+]=10^{(-1.5)}=0.0316M$

Molarity is defined as the amount of solute expressed in the number of moles present per liter of solution. The units of molarity are mol/L. The formula used to calculate molarity:

$\text{Molarity of solution}=\frac{\text{Number of moles of solute}\times 1000}{\text{Volume of solution (mL)}}$ .....(2)

We are given:

Volume of solution = 15.0 mL

Molarity of HCl = 0.0316 M

Putting values in equation 2:

$0.0316=\frac{\text{Moles of HCl}\times 1000}{15.0}\\\\\text{Moles of HCl}=\frac{0.0316\times 15.0}{1000}=4.74\times 10^{-4}mol$

The chemical equation for the reaction of HCl and calcium carbonate follows:

$2HCl+CaCO_3\rightarrow H_2CO_3+CaCl_2$

By the stoichiometry of the reaction:

2 moles of HCl reacts with 1 mole of calcium carbonate

So, $4.74\times 10^{-4}mol$ of HCl will react with = $\frac{1}{2}\times 4.74\times 10^{-4}=2.37\times 10^{-4}mol$ of calcium carbonate

The number of moles is defined as the ratio of the mass of a substance to its molar mass.

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Moles of calcium carbonate = $2.37\times 10^{-4}mol$

Molar mass of calcium carbonate = 100.01 g/mol

Putting values in the above equation:

$\text{Mass of }CaCO_3=(2.37\times 10^{-4}mol)\times 100.01g/mol\\\\\text{Mass of }CaCO_3=0.0237g$

Hence, 0.0237 g of calcium carbonate would be required to neutralize the given amount of HCl

7 0

2 years ago

A factor that changes in an experiment from manipulation of the independent variable is the what?

melomori [17]

Manipulation of the independent variable should change the dependent variable, the value of which "depends" on the independent variable's change in value.

7 0

3 years ago

Suppose an egyptian mummy is discovered in which the amount of carbon-14 present is only about oneone-fifthfifth the amount fo

poizon [28]

We are given the following equation:

y = y0 e^-0.0001216 t

where y = 1/5 y0, y0 is the original amount

So solving for time t:

1/5 y0= y0 e^-0.0001216 t

t = 13,235.51 years

So the human died about 13235.5 years ago

3 0

3 years ago

What was formed as result of diverging plates

irina [24]

It causes earthquakes say you had to glass plates you eat from and smash them together and they make a loud sound and brake into each other thats like the diverging plates

6 0

3 years ago